Floor polishers, and particularly polishers which are electrically operated, are known in the art and have been used for some time for polishing and buffing floors. Such machines are used particularly for commercial applications. Typically such machines include an operator's handle extending upwardly and rearwardly from a pair of mounting wheels. A machine housing having a buffing pad mounted for circular rotation about a generally vertically extending, centrally disposed axis extends forwardly from the mounting wheels.
In some prior art structures, the buffing surface of the pad defines a plane which is not tangent to the mounting wheels at their intersection with the floor surface. Consequently, with structures such as this, only a portion of the pad engages the floor.
Attempts have been made to effect and maintain full pad contact with the floor by positioning the pad so that its surface does define a plane which is tangent to the mounting wheels at their intersection with the floor. Frequently, however, the operator handle is disposed at a fixed angular relationship to the horizontal. For example, the handle may extend upwardly from the horizontal at an angle of 45 degrees thereto. As a machine of this type is being manuvered by its operator, a pushing motion upon the handle in a forward direction will cause the rearward edge of the pad to be lifted from the floor, to some extent, until the inertia of the machine is overcome.
In newer machines, attempts have been made to solve this problem by providing a handle which is pivotally mounted for movement about an axis about which the mounting wheels rotate. As the operator applies force to the machine by pushing it in a forward direction, some of the force is attenuated by the handle pivoting about the axis, and not as great a tilting movement is imparted to the buffing pad. Consequently, a greater percentage of the pad's surface will stay engaged with the floor than would if were the handle mounted at a fixed angle.
In all of the structures heretofore described, however, disengagement of at least a portion of the pad will occur, at least for a short period of time, to one degree or another. The consequences are the same in all cases but commensurate with the measure of pad disengagement with the floor. With full pad engagement, external forces on the machine are substantially equalized, and the machine will not tend to drift in any one direction. When, however, a portion of the pad, such as the rear portion thereof, becomes disengaged from the floor and elevated thereabove, a side torque will be applied to the machine, and it will tend to drift to one particular side.
When the machine tends to drift in one particular direction, more effort is required on the part of the operator of the machine to guide it where he desires. At low pad rotational speeds, the additional effort required of the operator may not be particularly significant. At high speeds, however, significant fatigue can be induced.
Additionally, when the load is not distributed throughout the full surface of the pad, the machine will tend to "chatter." This chattering, or vibration, causes uneven wear of the pad and additionally induces fatigue in the operator.
Finally, when full pad engagement is not effected, the machine will tend to draw large amounts of current. Draws in excess of 15 amperes are not uncommon with prior art machines.
It is to these deficiencies in the art that the invention in accordance with the present application is directed. It provides a structure which, as the machine is urged forward, resists raising of the rearward edge of the pad and maximizes full engagement of the buffing surface of the pad with the floor.